1. Field of the Invention
This invention relates to the field of analog signal record and playback using nonvolatile memory.
2. The Background Art
The use of recording systems for the storage and playback of audio messages is well known. Conventional recording systems are roughly categorized into two areas, those using magnetic streaming tape as the storage media, and those using semiconductor memory devices as the storage media.
Conventional systems using streaming magnetic tape as the storage media generally take an input signal generated by a microphone, amplify it, filter it in preparation for storage, and then record the signal onto magnetic tape provided for that purpose. Playback of the recorded signals may be accomplished by a user of the system using hand-operated controls provided for that purpose.
In order that a user of the system may operate the recording device, controls are provided so that a user may select such functions as record, playback, erase, power on, fast forward, fast reverse, pause, and stop. Using these functions, a user is able to record new messages, review or erase old messages, and perform other functions. Although these recording systems are useful for their intended purposes, they are often too complex and large to be used as hand-held devices, and are difficult to store in a person's pocket. It is therefore beneficial to provide a system wherein the operation of the system can be simplified, but where all normal functions are available for use in more complex situations.
Digital voice recording systems using semiconductor devices as the storage media typically amplify the incoming microphone audio, digitize the amplified signal using an analog-to-digital converter (ADC), and then store the resulting digital data in a semiconductor memory device. As in a conventional system which uses a magnetic tape for storage, the user may request the playback of a recorded signal in the digital system using controls provided for that purpose. Initiating the playback of a message typically causes the system controller to access the memory, process the information stored there through a digital-to-analog converter, amplify the resulting analog signal, then route the signal to an output device such as a speaker.
One such conventional device is described in U.S. Pat. No. 4,890,250 to Simko. In this system, eight command input buttons control the operation of system functions, include power on, record, playback, erase, fast forward, fast reverse, pause, and stop functions. Though useful for its intended purposes, due to the complexity of its 8-button command interface, this system is inadequate for applications requiring minimal complexity such as in a hand-held system which might be stored in a person's pocket. Therefore, it would be advantageous to provide a record and playback system which utilizes simplified user controls.